How can I deactivate Bluetooth on system startup?
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From ubuntu 16.04 onwards systemd manages startup services like bluetooth ... 

to view current status issue following in a terminal:
sudo systemctl status bluetooth.service 


to deactivate bluetooth on startup issue this:
sudo systemctl disable bluetooth.service


then on next reboot bluetooth will not be active ... to enable bluetooth issue ( then reboot )
sudo systemctl enable bluetooth.service

Date: June 4th, 2020
From: https://askubuntu.com/questions/67758/how-can-i-deactivate-bluetooth-on-system-startup